Duplex and diplex telegraphy



(No Model.) 2 Sheets-Sheet 1.

M. M. DAVIS.

DUPLEX AND DIPLEX TELEGRAPHY'.

No. 541,994. Patented July 2, 1895.

2 SheetsSheet 2..

(No Model.)

M. M. DAVIS. DUPLEX AND DIPLEX TELEGRAPHY. No. 541,994. Patente L 1895.

, Unites STATES MINOR M. DAVIS, OF BROOKLYN, NEW YORK.

Dl JPLEX AND DIPLEX TELEGRAPHY.

SPECIFICATION forming part of Letters Patent No. 541,994, dated July 2, 1895.

Application filed April 1 8, 1 8 95 To all whom it may concern.-

Be it known that I, MINOR M. DAVIS, a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have made certain new and useful Im-. provements in Duplex and Diplex Telegrae phy, of which the following is a specification.

The object of my invention is to provide a transmitting device of such a character that the spark, heat, and fusion existing and liable to occur in the use of dynamo-electric machinery or equivalent low-resistance sources, such as secondary batteries, is rendered harmless or obviated.

My improvement is specially useful in a pole-changing transmitter where the succes sion of currents to line is abruptly changed from a maximum positive to a maxim um negative.

In transmitters of the class described it is desirable and even necessary to employ such a combination of levers that the emitted sound shall be sharp, distinct, and readable, while the tendency to chatter or rattle when the lever engages with its stop shall be minimized. If the lever of a transmitter ohatters or rattles, sparking and fusing at the contact points are aggravated and extremely troublesome. To avoid this it is necessary to limit the length of the stroke to as short an excursion as possible, while the dots and dashes must not be shortened and the sound must be sufficiently loud or well identified.

My invention embodies the employment of fixed contact-points with movable contactpoints, the latter consisting of unequally-piv: oted spring-retracted levers so arranged that the longer arm of the lever shall engage with the contact-stop and the shorter arm of the lever shall engage with the actuating-lever or armature-bar, by means of which the levers are operated, either directly or through the medium of an electromagnet and a local circuit. By this arrangement of lovers a slight extent of movement of the actuating-lever producesa wide, abrupt, and sudden opening at the contact-points, and even if the actuatin g-lever rattles or chatters its slightest movement at its pointof engagement with the contact-levers results in an extended, abrupt, and sudden opening at the contact-point, an opening too great to permit of sparking, accomserial No. 546,168- (No model.)

plished with the utmost rapidity of move ment.

I have found my transmitter especially use ful in connection with the arrangement of dynamos devised by Francis W. Jones, in which four separate machines are employed, one pair being of high electromotive force and opposite polarity and one pair of low electromotive force and opposite polarity. In connection with these dynamos there are employed two dependent pole-changing transmittersthat is, the transmitters move together or coincidently, the one operating to reverse the polarity of current from one pair of dynamos, the other performing the same function for the other pair of dynamos, and an independenttransmitter operates to put one orthe other pair of dynamos in connection with the main line.

The accompanying drawings illustrate my invention.

Figure 1 shows my improved transmitter and its application to a polar duplex, and Fig. 2 shows my improved transmitter and its application to a diplex telegraph arrangement.

In both figures P is a pole-changing transmitter. There are two movable contacts consisting of two unequally pivoted levers a; and y, pivoted at 4.0 and 4.1, respectively, the location of the fulcrum or pivot being about two-thirds the length of the lever from the fixed electrical contacts 2 and 3. The operating or actuating lever a mechanically connects or contacts with the shorter arms of said levers through the medium of the rod of insulating material 1'. It is to be noticed that the length of t is suchthat when 00 contacts with 2 and y is separated from 3, the said mechanical connecting piece t' is slightly separated from 00, and vice versa. The two levers as and y are spring retracted, the retracting force being applied to the shorter arms, and in the embodiment of my invention illustrated, one spring 8 is employed with a proper adjusting device to draw the shorter ends of the two levers toward each other. The two levers are shown electrically united, forming the movable terminal of the line, while the fixed contacts 2 and 3 form, respectively, the terminals of two dynamos d and d of opposite polarity, respectively.

S is a well-known polarized relay, differena. The contact points 2 and :r are-separatedv with an abruptness and snap characteristic'of the action of a spring, and it results from this that any wavering, and any tendency to chatter, or rattle, on, the part of the lever a will be ineffective to produce sparkingat contactpoint 2, because any movement due to a,- separating i-t from its upper limit stop, has moved contact mabruptly,separating it from point 2 sufficiently to break any are, or tendency to arc, that might otherwise result. movementof the lever to breaks the'con'tactbetween the lever y and contact-point 3 in the same way. Following the break between contactsw and 2, contact is made between ft and 3, the dynamo of negative polarity being thus substituted for the dynamo of positive polarity in connection with the line, and the polarized relay 'S responds in a manner well understood in the art.

Referring to Fig. 2, I have shown my polechanging transmitter in combination with the arrangement for diplex transmission devised by Francis IV. Jones. d is a dynamo-machine of low electromotive force and positive polarity. d is asimilar machine of the same electromotive force and negative polarity. D and D are dynamos of high electromotive force and positive and negative polarity, respectively. P is my improved pole-changing transmitter, herein-before described. The actuating-lever a carries a supplemental lever -I, from which-itis insulated. The lever Iis the actuating-lever of a dependent transmitterincluding the movable contact and the fixed contact a. T is the well-known form of continuity-preserving transmitter composed of hooked lever 9, carrying the insulated spring 10, having the fixedcontact 11. S is a polarized differential relay. N is a neutral differential relay, and R is an artificial resistance, all'i ncluded-in themain line L. The two polechanging transmitters are operated by an e'lectro'mag'net, local circuit, and key, and the independent transmitter T is similarly operated. Dynamo D is connected with fixed contact 3 of transmitter 2P through the resistance 33 by the wire 23. Dynamo D is connected through resistance 32 by wire 2-2 with the fixed contact 2 of said transmitter. The levers w and y are electrically united and are connected by the main-line fragment 1 with the 'fixed contact 11 of the transmitter T. Dynamo d is connected through resist- T-he return ance 31 and wire 21 with fixed contact 6 of the dependent transmitter. Dynamo d is connected through resistance 30 and wire 20 with lever I of the dependent transmitter. The movable contact 0 of the dependent transmitter is connected through the main-line fragment 1 with lever 9 of transmitter T. The main line L is connected with insulated spring 10 of transmitter T.

When transmitter T is operated, main line L is alternately connected through 10, 9, and l with the dependent transmitter and low electromotive force dynamos, and through 1'0, 1'1, and l with levers or and y and the high electromotive force dynamos D and D. In the latter case-the operation of the transmitter P rapidly changes the line from the maximum positive to the maximum negative dynamo and the sparking heretofore incident to such changes-is obviated and avoided by the sudden, abrupt, and extended break between t he levers a; and y and the fixed contacts 2 and 3, respectively, and any inequality in the action of the actuating-lever a is rendered harmless by the arrangement of the unequally-pivoted leversan'd the fixed contacts located at t-h'ee-nd of the longer arms thereof.

I may ins-niate-tl-ie levers or and y from each other and connect them to the two dynam'os, respectively, and I may electrically unite the fixed contacts 2 and -3,con necting them to the main line Without departing from my invention; and I may substitute secondary batteries for the dynamo-machines shown, as I believe them to be-su-bs-tanti'al equivalentsas sources of electrical energy, on account of their low internal resistance.

WVhat I claim, and desire to secure by Letters Patent, is

-1. in a duplex or 'diplex te legra'ph the combination atthe re'ceiv-ingstation of an electromagnetic receiving instrument located in a main line, and at the transmitting station a transmitter located in said main line, composed of a fixed contact, a movable contact consisting of an unequally pivoted lever the longer arm'of which is in position to engage with said fixed contact, an actuating lever mec'hanicallycon-nectin g with the shorter arm of the first named lever, an electro-magnet and 'local circuit-for controlling'saidactuatin g lever, a retractor for the unequally pivoted I lever normally tend-ing 'to hold it in engagement'with said fixed contact, an electrica lconn'ection betweenthe main line and oneof said contacts and an-elec'trical connection between the terminal of a grounded-dy'namo-electric machine and theot-her-contact, all arranged and operating substantially as described.

2. In a duplex o'r diplex telegrap'h, at the transmitting stat-ioma pole changing transm' itter consisting of two fixed contact points connected "with dynamo-electric generators or oth'ersui tablesources of electricity respectively, a movable contactconsisting of an unequally-pivoted lever,thelongerarm of which is in position to contact with a fixed dynamo terminal or source of electricity, an electromagnet, an armature therefor mechanically connecting with the shorter arm of the first named lever, and an electrical connection between the main line and said first named lever, substantially as described.

3. In a duplex or diplex telegraph, at the transmitting station, a transmitting device consisting of two fixed contact points, two movable contact points formed of two similar, unequally pivoted, spring retracted levers, an actuating lever mechanically connecting with the shorter arms of the two first named levers, electrical connections between the main line and one pair of contact points, between one of the second pair of contacts and a positive dynamo pole or source, and between the other contact of said pair and a negative dynamo pole or source, substantially as described.

4. In a duplex or diplex telegraph the combination of a polarized receiving instrument in the'inain line at the receiving station; and at the transmitting station a pole changing transmitter consisting of two fixed contact points forming respectively, the terminals of dynamos or sources of electricity of opposite polarity, a pair of similar, unequally pivoted, spring retracted levers electrically connected together and to the main line, the longer arms of said levers being in position to engage with said fixed contacts, respectively,

an actuating lever mechanically connected with the shorter arms of said levers and means for operating said actuating lever, substantially as described. I

5. In a diplex telegraph the combination, at

the receiving station, of two receivinginstruments in the main line, one responsive to variations in intensity, the other responsive to variations in polarity of the main line current;

at the transmitting station, two dynamos or sources of electricity of high electro-motiveforce and respectively opposite polarity, two

dynamos or sources of electricity of low electro-motive-force and respectively opposite polarity, a pole changing transmitter consisting I a of two unequally pivoted, spring retracted leof movement, an electrical connection between two of said contacts and the terminals of the low electro-motive-force dynamos or sources, respectively, an electrical connection between the remaining one of the last named contacts and a contact point in said independent transmitter, and an electrical connection between a third contact point in said independent transmitter, and the main line, the whole being so arranged that the operation of the pole changing transmitters reverses the polarity of the dynamos or sources of electricity of both pairs and the operation of the independent transmitter determines which pair of dynamos or sources of electricity shall be placed in connection with the main line, substantially as described.

MINOR M. DAVIS. Witnesses:

W. S. PLACE, THEODORE L. CUYLER, Jr. 

